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作者在系统分析了1976年尤陵地震所在区域的地层学、岩石学、构造学、地貌学、地球物理学等方面资料的基础上指出,该地震位于一个主要是新生代发育的变质带、岩浆岩带、褶皱带、垂直形变带(包括隆起带和沉降带)、地震带和重力梯度带之中。这样一个巨型构造带正是印度板块和欧亚板块碰撞的产物,它在震中区之北由南北向转为南西向。主震机制的主压应力轴垂直于这个构造带,揭示了该地震是这两大板块相对运动的直接产物。 另外,本文在全面分析震中区地质资料基础上,从侵入岩脉、破碎带和小断层的相对集中位置和排列方式,以及对苏帕河发育的控制作用,肯定了苏帕河断裂的存在并描绘出所在位置;依据余震分布和烈度分布,构造应力场和主震应力状态的一致性,指出苏帕河断裂是这次地震的发震构造。 本文中还给出了震区构造应力场。
Based on the systematic analysis of the data of stratigraphy, petrology, tectonics, geomorphology and geophysics in the area where the Euling earthquake in 1976 was located, the author pointed out that the earthquake is located in a metamorphic zone mainly of Cenozoic development, Rock belt, fold belt, vertical deformation zone (including the uplift zone and subsidence zone), seismic zone and gravity gradient zone. Such a giant structural zone is just the product of the collision between the Indian plate and the Eurasian plate, which changes from north to south in the epicenter area to a southwest direction. The principal compressive stress axis of the mainshock mechanism is perpendicular to this tectonic belt, revealing that the earthquake is a direct product of the relative motion of the two plates. In addition, on the basis of comprehensive analysis of the geologic data of the epicenter area, this paper affirms the existence of the Supa fault from the relative concentration position and arrangement of the invaded dikes, the fractured zone and the minor fault, and the control over the development of the Supa River According to the distribution of aftershocks and the distribution of intensity, the consistency between the stress field and the stress state of the main shock is constructed. It is pointed out that the Supahe fault is the seismogenic structure of this earthquake. In this paper, the tectonic stress field in the earthquake zone is also given.